Consistent Null Handling

One of the posts on "Cure for Madness" brought up consistent null =
handling which Oracle does not do. For instance,
"Select Column1 + Column2 from TableA;" returns null if either or both =
columns are null. However "Select sum(Column1) from table A" will =
return a value if there are non-null values in the column. Is this true =
for all SQL versions? =20